From: Vivek Goyal <vgoyal@redhat.com>
Date: Thu, 19 Dec 2013 01:08:31 +0000 (-0800)
Subject: kexec: migrate to reboot cpu
X-Git-Tag: v3.13-rc5~23^2~23
X-Git-Url: http://pileus.org/git/?a=commitdiff_plain;h=c97102ba96324da330078ad8619ba4dfe840dbe3;p=~andy%2Flinux

kexec: migrate to reboot cpu

Commit 1b3a5d02ee07 ("reboot: move arch/x86 reboot= handling to generic
kernel") moved reboot= handling to generic code.  In the process it also
removed the code in native_machine_shutdown() which are moving reboot
process to reboot_cpu/cpu0.

I guess that thought must have been that all reboot paths are calling
migrate_to_reboot_cpu(), so we don't need this special handling.  But
kexec reboot path (kernel_kexec()) is not calling
migrate_to_reboot_cpu() so above change broke kexec.  Now reboot can
happen on non-boot cpu and when INIT is sent in second kerneo to bring
up BP, it brings down the machine.

So start calling migrate_to_reboot_cpu() in kexec reboot path to avoid
this problem.

Bisected by WANG Chao.

Reported-by: Matthew Whitehead <mwhitehe@redhat.com>
Reported-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Tested-by: Baoquan He <bhe@redhat.com>
Tested-by: WANG Chao <chaowang@redhat.com>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 8e00f9f6f96..9e7db9e73cc 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -43,6 +43,7 @@ extern int unregister_reboot_notifier(struct notifier_block *);
  * Architecture-specific implementations of sys_reboot commands.
  */
 
+extern void migrate_to_reboot_cpu(void);
 extern void machine_restart(char *cmd);
 extern void machine_halt(void);
 extern void machine_power_off(void);
diff --git a/kernel/kexec.c b/kernel/kexec.c
index d0d8fca5406..9c970167e40 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -1680,6 +1680,7 @@ int kernel_kexec(void)
 	{
 		kexec_in_progress = true;
 		kernel_restart_prepare(NULL);
+		migrate_to_reboot_cpu();
 		printk(KERN_EMERG "Starting new kernel\n");
 		machine_shutdown();
 	}
diff --git a/kernel/reboot.c b/kernel/reboot.c
index f813b347464..662c83fc16b 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -104,7 +104,7 @@ int unregister_reboot_notifier(struct notifier_block *nb)
 }
 EXPORT_SYMBOL(unregister_reboot_notifier);
 
-static void migrate_to_reboot_cpu(void)
+void migrate_to_reboot_cpu(void)
 {
 	/* The boot cpu is always logical cpu 0 */
 	int cpu = reboot_cpu;